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In the present article, the graft copolymerization of 4‐vinyl pyridine onto guar gum initiated by potassium peroxymonosulphate/ascorbic acid redox pair in an aqueous medium was studied gravimetrically under a nitrogen atmosphere. Grafting ratio, grafting efficiency, and add on increased on increasing the concentration of potassium peroxymonosulphate from 5.0 × 10−4 to 10 × 10−4 mol/L and ascorbic acid concentration from 0.4 × 10−3 to 2.0 × 10−3 mol/L. On increasing the hydrogen ion concentration from 2.5 × 10−3 to 10.0 × 10−3 mol/L, grafting ratio, efficiency, add on and conversion were increased. Maximum grafting was obtained when guar gum and monomer concentration were 1.0 g/L and 20.0 × 10−2 mol/L, respectively. An increase in temperature from 30 to 35°C increased the grafting ratio, but conversion and homopolymer decreased. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

The aim of this study was to examine the synthesis of a graft copolymer of chitosan and methacrylic acid (MAA) by free-radical polymerization with a potassium peroxymonosulfate/cyclohexanone (CY) redox system in an inert atmosphere. The optimum reaction conditions affording maximum grafting ratio (%G), grafting efficiency (%E), add on (%A), and conversion (%C) were determined. The grafting parameters were found to increase with increasing concentration of MAA up to 24 Â 10 À2 mol/dm 3 , but thereafter, these parameters decreased. With increasing concentration of peroxymonosulfate from 0.6 Â 10 À2 to 1.2 Â 10 À2 mol/dm 3 , %G, %A, and %E increased continuously. All of these grafting parameters increased with increasing concentration of CY up to 1.2 Â 10 À2 mol/dm 3 , but beyond this concentration, the grafting parameters decreased. With vari-ous concentrations of chitosan from 0.6 to 1.4 g/dm 3 , the maximum %G, %A, and %E were obtained at 1.4 g/dm 3 . %G, %A, and %C decreased continuously with various concentrations of hydrogen ions from 2 Â 10 À3 to 6 Â 10 À3 mol/dm 3 . The grafting parameters increased with increasing temperature up to 35 C, but thereafter, these parameters decreased. With increasing time period of reaction from 60 to 180 min, %G, %A, and %E increased up to 120 min, but thereafter, these parameters decreased. The graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis.